August in a Tokyo apartment: cooling and AC problems

If your Tokyo apartment stays uncomfortably hot with the air conditioner running, check the selected mode and contact the company you're renting from promptly. Don't spend several nights trying lower and lower remote settings without telling anyone.

For a booking you haven't made yet, ask about the bedroom itself. “Air conditioning included” may leave you wondering whether the bedroom has its own unit or relies on air from another room. That matters when you want to close the door to sleep or work.

Ask how the sleeping room is cooled

Request the floor plan, the location of each air-conditioning unit and any guidance for keeping the bedroom comfortable. If one unit serves several spaces, ask how the arrangement works with internal doors closed. A photograph of the living-room unit doesn't answer that question.

Window direction, shading and curtains can help explain what the room is like. For a west-facing bedroom, ask about afternoon sun and how the cooling copes with it.

Ask who responds to a cooling failure and what happens if a repair cannot be completed promptly. Get the after-hours number if you’ll arrive in the evening or at the weekend. Keep the answer with your booking confirmation.

Check the room, not just the remote

The number on the remote is a target setting. It isn't a measurement of the air beside your bed. Use a thermometer near your bed or desk to measure the temperature you’re experiencing.

The Environment Ministry's heat guidance recommends checking room temperature and humidity and notes that temperature can vary around a room even with air conditioning running. Record the conditions where you sleep or work, rather than placing the thermometer directly in the cold air outlet or sunlight.

For example, you could write: “The bedroom thermometer reads 29°C at 22:00 after an hour on cooling at a 25°C setting; the bedroom door is closed.” Those details give the maintenance team more to work with than “the AC is weak.” These example temperatures don't tell you whether the room is safe or why the air conditioner isn't cooling it.

Cooling and dry mode do different jobs

冷房 (reibō) is cooling; 除湿 (joshitsu) or ドライ (dorai) is dehumidification. Use the actual remote labels and manual, since icons and controls vary.

Daikin explains that cooling prioritises lowering temperature, while dehumidification prioritises removing moisture. Some dry modes cool the room as they remove moisture. Others warm the air again before blowing it back into the room.

That means “always use dry mode when it's humid” isn't a good rule for a hot bedroom. Start with cooling when you need to lower the temperature. If the room is cool enough but still feels damp, check the model's dry-mode options and see whether the room becomes less damp without getting too cold. Don't assume all brands or models behave alike.

Cooling also removes moisture as air passes over the cold surface inside the unit. Daikin's rainy-season explanation describes how that moisture leaves through the drain hose. If the room stays damp, ask the rental company to check the settings and equipment.

Check settings and airflow

Close windows and external doors while cooling, and use the supplied curtains to reduce direct sun. Keep furniture, bags and curtains clear of the indoor unit's intake and outlet. Check whether the remote is on a timer, fan-only setting or another mode you didn't intend.

If you can see the outdoor unit safely from somewhere you are allowed to stand, look for luggage or other items blocking it. Send a photograph of anything in the way if you can take one safely. Don't climb out, remove a cover or reach into equipment.

A fan can help circulate air while you arrange help with the air conditioner. The Environment Ministry suggests air circulation where room temperatures are uneven. Keep the fan stable and the cord out of the walking route, and ask before moving heavy furniture to change airflow.

Check the manual before cleaning a removable filter, and ask the rental company which maintenance is yours to do. Don't spray cleaner into the appliance or open electrical parts. Leave repairs to the qualified technician arranged by the rental company.

Know which contact handles a fault after hours

Sakura House's FAQ tells residents to report faults promptly and directs them to its sister hotel company for assistance outside office hours. That gives you someone to contact after hours, but it does not guarantee that an AC technician will arrive that night.

Ask your rental company who to call after hours and whether that person can arrange a repair or another room. Save both contacts if daytime and overnight support are different. If the bedroom is too hot to sleep in, ask where you can stay while waiting for the repair.

What to include in a cooling-fault report

Include the apartment and room, when the problem began, remote mode and setting, measured room temperature if available, any error code, and whether air is coming out. Say whether another room's unit works and attach photographs of the remote and model label if you can reach them safely.

The bedroom isn't cooling adequately. At [time], the room reads [temperature], with [mode and setting] selected since [time]. The windows are closed and [door position]. I've attached the display and model photographs. What should I check next, and when can someone come to repair it? Where can I stay if the bedroom cannot be cooled tonight?

If water is leaking indoors, the unit smells burnt, sparks or behaves unusually, stop using it when safe and contact the emergency maintenance number.

Move somewhere cooler if the room remains too hot

Heat illness can happen indoors. The Environment Ministry advises using air conditioning appropriately and moving to a cool place if symptoms develop. Don't delay cooling yourself while waiting for the rental company to reply.

If you need an ambulance, call 119. The apartment emergency guide explains what to tell the dispatcher. If the immediate issue is an uncomfortably hot room, ask the company where you can stay while waiting for repairs, and agree what it will pay before booking accommodation you expect it to cover.

Keep the maintenance messages with any agreement about another room or reimbursement. Once the repair or setting change is made, check the bedroom again under the conditions that caused the problem, including the door position you'll use overnight.